mix bed water polisher is a process of absorption of mineral ions in the water by using ion exchange resin. The water from the mix bed polisher process is used for a variety of needs, especially for industry. Industries that use demin water include the steam power plant, the semiconductor industry, and also the pharmaceutical industry.
There are two types of resin columns commonly used in the water demineralization process. Both are Single Bed and Mixed Exchange Ion Resin Bed. Single Bed means that in one column there is only one type of resin, that is only cation resin or anion resin. Whereas the Mixed Bed column contains a mixture of cation and anion resins. <h3
Multi-stage demineralization process, water will pass through the cation resin to bind the positive mineral ions. This process is followed by the release of H + ions into the water. If R and K2 + are resin ion and positive mineral ion molecules, then the ion exchange reaction that occurs in the resin column is as follows: 2 R-H + K2 + → R2K + 2 H + Calcium ions dissolved in water are usually in the form of calcium bicarbonate.
When calcium ions are bound to a resin molecule, calcium bicarbonate will split to form water and carbon dioxide molecules. 2 R-H + Ca (HCO3) 2 → R2Ca + 2 H2 + 2 CO2 The carbon dioxide molecule produced by the above reaction is released through a CO2 removal system. H + ions released into water bind to dissolved anions in the water. So the hydrogen ion reaction will produce strong acids such as sulfuric acid, hydrochloric, and nitric acid. To remove this acidity, water is further flowed into the anion resin.
When passing through anion resin, negative ions dissolved in water will be bound by resin molecules followed by the release of OH- ions. If A is a negative ion dissolved in water, the reaction that occurs in anion resin is as follows: 2 R-OH + A2- → R2A + 2 OH– Eventually the H + and OH- ions will react to form new water molecules: H ++ OH– → H2O Another form of demineralization system variation is by using strong and weak anion resin columns. This system produces the same output quality using only one anion resin.
The advantage of this system is that it is more economical to have to bind strong anions such as sulfate and chlorite, because during the regeneration of the resin, a concentrated NaOH solution coming out of the strong resin column is sufficient to regenerate a weak resin anion. To deal with the same amount of strong anion dissolved in water, the amount of NaOH solution needed to regenerate the two resin anions is less than NaOH regenerating the system with one resin anion.
In some industrial needs, sometimes it takes not one stage of the cation and anion exchange process. In some processes, raw water is passed up to two or three cations and resin column anions. To summarize the process, each ion exchange stage can be used one column of resin which contains cation and anion resins at once. At the end of the demineralization process, you will get very pure water. This system is very suitable for use in factories using high pressure boilers, as well as the electronics industry for the needs of washing transistors and other electronic components.
If all the resin molecules have binded their target ions, the resin is said to have reached its saturation point. To be able to reuse the resin, a regeneration process needs to be done. Following are the general stages of the regeneration process of single-bed cation or anion resins:
Finally, rinse the resin by flowing demin water at the same speed as the treatment process, until the output water from this resin matches the desired quality. For the mixed-bed resin regeneration process, it requires more steps.
The following are the stages: